1. Field of the Invention
The invention pertains to a drive unit for a hybrid vehicle and to a method for the assembly of such a drive unit.
2. Description of the Related Art
A drive unit of the general type in question is already known from DE 10 2006 053 660 A1. The drive comprises an internal combustion engine, an electric machine, a friction clutch, and a torsion damper arranged in a row in the axial direction, where the clutch can be used to disconnect the takeoff shaft of the internal combustion engine from the other assemblies.
Because of the axially sequential arrangement, it is logical to undertake the assembly of the overall drive unit in the corresponding way, that is, in the order in which the components are arranged. When this approach is used, the electric machine, including the actuating device for the friction clutch, is preassembled first and then attached to the housing of the internal combustion engine. In the next step, the clutch is mounted, its clutch plate housing being connected nonrotatably to the rotor carrier of the electric machine and its friction lining disk being attached by way of a clutch hub to the crankshaft of the internal combustion engine. Then the torsion damper with its housing can be attached to the pressure plate housing of the friction clutch.
For a motor vehicle manufacturer, this assembly concept is very time-consuming and costly. It is also desirable with respect to the assembly of the entire vehicle power train to use two or more components which have been preassembled at some other manufacturing site. As a result of such preassembly the assembly work required to build the drive unit can be significantly reduced and costs decreased.
In the case of the drive unit explained above, the friction lining disk is attached axially to the crankshaft by additional elements, special attention must be paid during the assembly of the drive unit to the correct axial positioning of the clutch to guarantee that the clutch will function properly. In contrast, the friction lining disk of a conventional friction clutch is guided on the transmission input shaft so that it can be shifted axially by means of a radially toothed clutch hub, where, when the clutch is being engaged, the friction lining disk with its hub automatically adjusts itself. In the present case, however, adjusting the friction lining disk so that it is in the correct axial position requires that the disk be checked to make sure that it can move freely, and for this purpose at least the electric machine and the clutch must be attached to the internal combustion engine. In addition, insofar as it has been necessary to remove at least the clutch plate housing and possibly even the previously installed torsion damper, it will also be necessary to reinstall these elements or components after the axial position of the friction lining disk has been adjusted